diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/Changelog.md | 38 | ||||
| -rw-r--r-- | docs/FAQ.md | 12 | ||||
| -rw-r--r-- | docs/INSTALL.md | 19 | ||||
| -rw-r--r-- | docs/env_variables.md | 121 | ||||
| -rw-r--r-- | docs/ideas.md | 57 | ||||
| -rw-r--r-- | docs/life_pro_tips.md | 4 | ||||
| -rw-r--r-- | docs/perf_tips.md | 8 | ||||
| -rw-r--r-- | docs/sister_projects.md | 4 | ||||
| -rw-r--r-- | docs/status_screen.md | 2 |
9 files changed, 115 insertions, 150 deletions
diff --git a/docs/Changelog.md b/docs/Changelog.md index 72c8952c..9de03e78 100644 --- a/docs/Changelog.md +++ b/docs/Changelog.md @@ -9,23 +9,43 @@ Want to stay in the loop on major new features? Join our mailing list by sending a mail to <afl-users+subscribe@googlegroups.com>. -### Version ++2.67d (develop) +### Version ++3.00a (develop) + - llvm_mode/ and gcc_plugin/ moved to instrumentation/ + - all compilers combined to afl-cc which emulates the previous ones + - afl-llvm/gcc-rt.o merged into afl-compiler-rt.o + - afl-fuzz + - reading testcases from -i now descends into subdirectories + - allow up to 4 -x command line options + - loaded extras now have a duplicate protection + - instrumentation + - new llvm pass: dict2file via AFL_LLVM_DICT2FILE, create afl-fuzz + -x dictionary of string comparisons found during compilation + - not overriding -Ox or -fno-unroll-loops anymore + + +### Version ++2.68c (release) + - added the GSoC excellent afl++ grammar mutator by Shengtuo to our + custom_mutators/ (see custom_mutators/README.md) - or get it here: + https://github.com/AFLplusplus/Grammar-Mutator - a few QOL changes for Apple and its outdated gmake - afl-fuzz: - - Fix for auto dictionary entries found during fuzzing to not throw out + - fix for auto dictionary entries found during fuzzing to not throw out a -x dictionary - added total execs done to plot file - - AFL_MAX_DET_EXTRAS env variable added to control the amount of deterministic - dict entries without recompiling. - - AFL_FORKSRV_INIT_TMOUT env variable added to control the time to wait for - the forkserver to come up without the need to increase the overall timeout. + - AFL_MAX_DET_EXTRAS env variable added to control the amount of + deterministic dict entries without recompiling. + - AFL_FORKSRV_INIT_TMOUT env variable added to control the time to wait + for the forkserver to come up without the need to increase the overall + timeout. - bugfix for cmplog that results in a heap overflow based on target data (thanks to the magma team for reporting!) + - write fuzzing setup into out/fuzzer_setup (environment variables and + command line) - custom mutators: - - added afl_custom_fuzz_count/fuzz_count function to allow specifying the - number of fuzz attempts for custom_fuzz + - added afl_custom_fuzz_count/fuzz_count function to allow specifying + the number of fuzz attempts for custom_fuzz - llvm_mode: - - Ported SanCov to LTO, and made it the default for LTO. better + - ported SanCov to LTO, and made it the default for LTO. better instrumentation locations - Further llvm 12 support (fast moving target like afl++ :-) ) - deprecated LLVM SKIPSINGLEBLOCK env environment diff --git a/docs/FAQ.md b/docs/FAQ.md index 93a87a72..24942492 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -37,8 +37,8 @@ e.g. [Fuzzbench Report](https://www.fuzzbench.com/reports/2020-08-03/index.html) ## How to improve the fuzzing speed - 1. use [llvm_mode](docs/llvm_mode/README.md): afl-clang-lto (llvm >= 11) or afl-clang-fast (llvm >= 9 recommended) - 2. Use [persistent mode](llvm_mode/README.persistent_mode.md) (x2-x20 speed increase) + 1. use [instrumentation](docs/README.llvm.md): afl-clang-lto (llvm >= 11) or afl-clang-fast (llvm >= 9 recommended) + 2. Use [persistent mode](instrumentation/README.persistent_mode.md) (x2-x20 speed increase) 3. Use the [afl++ snapshot module](https://github.com/AFLplusplus/AFL-Snapshot-LKM) (x2 speed increase) 4. If you do not use shmem persistent mode, use `AFL_TMPDIR` to point the input file on a tempfs location, see [docs/env_variables.md](docs/env_variables.md) 5. Improve kernel performance: modify `/etc/default/grub`, set `GRUB_CMDLINE_LINUX_DEFAULT="ibpb=off ibrs=off kpti=off l1tf=off mds=off mitigations=off no_stf_barrier noibpb noibrs nopcid nopti nospec_store_bypass_disable nospectre_v1 nospectre_v2 pcid=off pti=off spec_store_bypass_disable=off spectre_v2=off stf_barrier=off"`; then `update-grub` and `reboot` (warning: makes the system more insecure) @@ -55,7 +55,7 @@ which is totally unsupported by most coverage aware fuzzers. The established method to fuzz network services is to modify the source code to read from a file or stdin (fd 0) (or even faster via shared memory, combine -this with persistent mode [llvm_mode/README.persistent_mode.md](llvm_mode/README.persistent_mode.md) +this with persistent mode [instrumentation/README.persistent_mode.md](instrumentation/README.persistent_mode.md) and you have a performance gain of x10 instead of a performance loss of over x10 - that is a x100 difference! @@ -180,10 +180,10 @@ afl-clang-fast PCGUARD and afl-clang-lto LTO instrumentation. b) For PCGUARD instrumented binaries it is much more difficult. Here you can either modify the __sanitizer_cov_trace_pc_guard function in - llvm_mode/afl-llvm-rt.o.c to write a backtrace to a file if the ID in + instrumentation/afl-llvm-rt.o.c to write a backtrace to a file if the ID in __afl_area_ptr[*guard] is one of the unstable edge IDs. (Example code is already there). - Then recompile and reinstall llvm_mode and rebuild your target. + Then recompile and reinstall instrumentation and rebuild your target. Run the recompiled target with afl-fuzz for a while and then check the file that you wrote with the backtrace information. Alternatively you can use `gdb` to hook __sanitizer_cov_trace_pc_guard_init @@ -200,7 +200,7 @@ afl-clang-fast PCGUARD and afl-clang-lto LTO instrumentation. remove from instrumentation, or just specify the functions you want to skip instrumenting. Note that optimization might inline functions! - Simply follow this document on how to do this: [llvm_mode/README.instrument_list.md](llvm_mode/README.instrument_list.md) + Simply follow this document on how to do this: [instrumentation/README.instrument_list.md](instrumentation/README.instrument_list.md) If PCGUARD is used, then you need to follow this guide (needs llvm 12+!): [http://clang.llvm.org/docs/SanitizerCoverage.html#partially-disabling-instrumentation](http://clang.llvm.org/docs/SanitizerCoverage.html#partially-disabling-instrumentation) diff --git a/docs/INSTALL.md b/docs/INSTALL.md index 766f24d7..fb7b5642 100644 --- a/docs/INSTALL.md +++ b/docs/INSTALL.md @@ -24,7 +24,7 @@ There are no special dependencies to speak of; you will need GNU make and a working compiler (gcc or clang). Some of the optional scripts bundled with the program may depend on bash, gdb, and similar basic tools. -If you are using clang, please review llvm_mode/README.md; the LLVM +If you are using clang, please review README.llvm.md; the LLVM integration mode can offer substantial performance gains compared to the traditional approach. @@ -52,10 +52,10 @@ sudo gmake install Keep in mind that if you are using csh as your shell, the syntax of some of the shell commands given in the README.md and other docs will be different. -The `llvm_mode` requires a dynamically linked, fully-operational installation of +The `llvm` requires a dynamically linked, fully-operational installation of clang. At least on FreeBSD, the clang binaries are static and do not include some of the essential tools, so if you want to make it work, you may need to -follow the instructions in llvm_mode/README.md. +follow the instructions in README.llvm.md. Beyond that, everything should work as advertised. @@ -97,27 +97,24 @@ and definitely don't look POSIX-compliant. This means two things: User emulation mode of QEMU does not appear to be supported on MacOS X, so black-box instrumentation mode (`-Q`) will not work. -The llvm_mode requires a fully-operational installation of clang. The one that +The llvm instrumentation requires a fully-operational installation of clang. The one that comes with Xcode is missing some of the essential headers and helper tools. -See llvm_mode/README.md for advice on how to build the compiler from scratch. +See README.llvm.md for advice on how to build the compiler from scratch. ## 4. Linux or *BSD on non-x86 systems Standard build will fail on non-x86 systems, but you should be able to leverage two other options: - - The LLVM mode (see llvm_mode/README.md), which does not rely on + - The LLVM mode (see README.llvm.md), which does not rely on x86-specific assembly shims. It's fast and robust, but requires a complete installation of clang. - The QEMU mode (see qemu_mode/README.md), which can be also used for fuzzing cross-platform binaries. It's slower and more fragile, but can be used even when you don't have the source for the tested app. -If you're not sure what you need, you need the LLVM mode. To get it, try: - -```bash -AFL_NO_X86=1 gmake && gmake -C llvm_mode -``` +If you're not sure what you need, you need the LLVM mode, which is built by +default. ...and compile your target program with afl-clang-fast or afl-clang-fast++ instead of the traditional afl-gcc or afl-clang wrappers. diff --git a/docs/env_variables.md b/docs/env_variables.md index c47d10e8..9d289f6d 100644 --- a/docs/env_variables.md +++ b/docs/env_variables.md @@ -5,13 +5,25 @@ users or for some types of custom fuzzing setups. See README.md for the general instruction manual. -## 1) Settings for afl-gcc, afl-clang, and afl-as - and gcc_plugin afl-gcc-fast +## 1) Settings for all compilers -Because they can't directly accept command-line options, the compile-time -tools make fairly broad use of environmental variables: +Starting with afl++ 3.0 there is only one compiler: afl-cc +To select the different instrumentation modes this can be done by + 1. passing --afl-MODE command line options to the compiler + 2. use a symlink to afl-cc: afl-gcc, afl-g++, afl-clang, afl-clang++, + afl-clang-fast, afl-clang-fast++, afl-clang-lto, afl-clang-lto++, + afl-gcc-fast, afl-g++-fast + 3. using the environment variable AFL_CC_COMPILER with MODE - - Most afl tools do not print any output if stdout/stderr are redirected. - If you want to save the output in a file then set the AFL_DEBUG +MODE can one of LTO (afl-clang-lto*), LLVM (afl-clang-fast*), GCC_PLUGIN +(afl-g*-fast) or GCC (afl-gcc/afl-g++). + +Because beside the --afl-MODE command no afl specific command-line options +are accepted, the compile-time tools make fairly broad use of environmental +variables: + + - Most afl tools do not print any ouput if stout/stderr are redirected. + If you want to have the output into a file then set the AFL_DEBUG environment variable. This is sadly necessary for various build processes which fail otherwise. @@ -24,6 +36,8 @@ tools make fairly broad use of environmental variables: will cause problems in programs built with -Werror, simply because -O3 enables more thorough code analysis and can spew out additional warnings. To disable optimizations, set AFL_DONT_OPTIMIZE. + However if -O... and/or -fno-unroll-loops are set, these are not + overriden. - Setting AFL_USE_ASAN automatically enables ASAN, provided that your compiler supports that. Note that fuzzing with ASAN is mildly challenging @@ -44,7 +58,7 @@ tools make fairly broad use of environmental variables: you instrument hand-written assembly when compiling clang code by plugging a normalizer into the chain. (There is no equivalent feature for GCC.) - - Setting AFL_INST_RATIO to a percentage between 0% and 100% controls the + - Setting AFL_INST_RATIO to a percentage between 0 and 100% controls the probability of instrumenting every branch. This is (very rarely) useful when dealing with exceptionally complex programs that saturate the output bitmap. Examples include v8, ffmpeg, and perl. @@ -55,19 +69,16 @@ tools make fairly broad use of environmental variables: Setting AFL_INST_RATIO to 0 is a valid choice. This will instrument only the transitions between function entry points, but not individual branches. + Note that this is an outdated variable. A few instances (e.g. afl-gcc) + still support these, but state-of-the-art (e.g. LLVM LTO and LLVM PCGUARD) + do not need this. + - AFL_NO_BUILTIN causes the compiler to generate code suitable for use with libtokencap.so (but perhaps running a bit slower than without the flag). - TMPDIR is used by afl-as for temporary files; if this variable is not set, the tool defaults to /tmp. - - Setting AFL_KEEP_ASSEMBLY prevents afl-as from deleting instrumented - assembly files. Useful for troubleshooting problems or understanding how - the tool works. To get them in a predictable place, try something like: - - mkdir assembly_here - TMPDIR=$PWD/assembly_here AFL_KEEP_ASSEMBLY=1 make clean all - - If you are a weird person that wants to compile and instrument asm text files then use the AFL_AS_FORCE_INSTRUMENT variable: AFL_AS_FORCE_INSTRUMENT=1 afl-gcc foo.s -o foo @@ -78,19 +89,24 @@ tools make fairly broad use of environmental variables: - Setting AFL_CAL_FAST will speed up the initial calibration, if the application is very slow -## 2) Settings for afl-clang-fast / afl-clang-fast++ / afl-gcc-fast / afl-g++-fast +## 2) Settings for LLVM and LTO: afl-clang-fast / afl-clang-fast++ / afl-clang-lto / afl-clang-lto++ -The native instrumentation helpers (llvm_mode and gcc_plugin) accept a subset +The native instrumentation helpers (instrumentation and gcc_plugin) accept a subset of the settings discussed in section #1, with the exception of: + - LLVM modes support `AFL_LLVM_DICT2FILE=/absolute/path/file.txt` which will + write all constant string comparisons to this file to be used with + afl-fuzz' `-x` option. + - AFL_AS, since this toolchain does not directly invoke GNU as. - TMPDIR and AFL_KEEP_ASSEMBLY, since no temporary assembly files are created. - - AFL_INST_RATIO, as we by default use collision free instrumentation. + - AFL_INST_RATIO, as we by default collision free instrumentation is used. + Not all passes support this option though as it is an outdated feature. -Then there are a few specific features that are only available in llvm_mode: +Then there are a few specific features that are only available in instrumentation: ### Select the instrumentation mode @@ -121,7 +137,7 @@ Then there are a few specific features that are only available in llvm_mode: None of the following options are necessary to be used and are rather for manual use (which only ever the author of this LTO implementation will use). - These are used if several seperated instrumentations are performed which + These are used if several seperated instrumentation are performed which are then later combined. - AFL_LLVM_DOCUMENT_IDS=file will document to a file which edge ID was given @@ -136,7 +152,7 @@ Then there are a few specific features that are only available in llvm_mode: - AFL_LLVM_LTO_DONTWRITEID prevents that the highest location ID written into the instrumentation is set in a global variable - See llvm_mode/README.LTO.md for more information. + See instrumentation/README.LTO.md for more information. ### INSTRIM @@ -154,7 +170,7 @@ Then there are a few specific features that are only available in llvm_mode: afl-fuzz will only be able to see the path the loop took, but not how many times it was called (unless it is a complex loop). - See llvm_mode/README.instrim.md + See instrumentation/README.instrim.md ### NGRAM @@ -165,7 +181,7 @@ Then there are a few specific features that are only available in llvm_mode: config.h to at least 18 and maybe up to 20 for this as otherwise too many map collisions occur. - See llvm_mode/README.ctx.md + See instrumentation/README.ctx.md ### CTX @@ -176,7 +192,7 @@ Then there are a few specific features that are only available in llvm_mode: config.h to at least 18 and maybe up to 20 for this as otherwise too many map collisions occur. - See llvm_mode/README.ngram.md + See instrumentation/README.ngram.md ### LAF-INTEL @@ -196,17 +212,17 @@ Then there are a few specific features that are only available in llvm_mode: - Setting AFL_LLVM_LAF_ALL sets all of the above - See llvm_mode/README.laf-intel.md for more information. + See instrumentation/README.laf-intel.md for more information. ### INSTRUMENT LIST (selectively instrument files and functions) - This feature allows selective instrumentation of the source + This feature allows selectively instrumentation of the source - Setting AFL_LLVM_ALLOWLIST or AFL_LLVM_DENYLIST with a filenames and/or function will only instrument (or skip) those files that match the names listed in the specified file. - See llvm_mode/README.instrument_list.md for more information. + See instrumentation/README.instrument_list.md for more information. ### NOT_ZERO @@ -220,27 +236,34 @@ Then there are a few specific features that are only available in llvm_mode: test. If the target performs only few loops then this will give a small performance boost. - See llvm_mode/README.neverzero.md + See instrumentation/README.neverzero.md ### CMPLOG - Setting AFL_LLVM_CMPLOG=1 during compilation will tell afl-clang-fast to - produce a CmpLog binary. See llvm_mode/README.cmplog.md + produce a CmpLog binary. See instrumentation/README.cmplog.md - See llvm_mode/README.neverzero.md + See instrumentation/README.neverzero.md -Then there are a few specific features that are only available in the gcc_plugin: +## 3) Settings for GCC / GCC_PLUGIN modes -### INSTRUMENT_FILE +Then there are a few specific features that are only available in GCC and +GCC_PLUGIN mode. - This feature allows selective instrumentation of the source + - Setting AFL_KEEP_ASSEMBLY prevents afl-as from deleting instrumented + assembly files. Useful for troubleshooting problems or understanding how + the tool works. (GCC mode only) + To get them in a predictable place, try something like: - - Setting AFL_GCC_INSTRUMENT_FILE with a filename will only instrument those - files that match the names listed in this file (one filename per line). + mkdir assembly_here + TMPDIR=$PWD/assembly_here AFL_KEEP_ASSEMBLY=1 make clean all + - Setting AFL_GCC_INSTRUMENT_FILE with a filename will only instrument those + files that match the names listed in this file (one filename per line). See gcc_plugin/README.instrument_list.md for more information. + (GCC_PLUGIN mode only) -## 3) Settings for afl-fuzz +## 4) Settings for afl-fuzz The main fuzzer binary accepts several options that disable a couple of sanity checks or alter some of the more exotic semantics of the tool: @@ -278,14 +301,6 @@ checks or alter some of the more exotic semantics of the tool: don't want AFL to spend too much time classifying that stuff and just rapidly put all timeouts in that bin. - - Setting AFL_FORKSRV_INIT_TMOUT allows yout to specify a different timeout - to wait for the forkserver to spin up. The default is the `-t` value times - `FORK_WAIT_MULT` from `config.h` (usually 10), so for a `-t 100`, the - default would wait `1000` milis. Setting a different time here is useful - if the target has a very slow startup time, for example when doing - full-system fuzzing or emulation, but you don't want the actual runs - to wait too long for timeouts. - - AFL_NO_ARITH causes AFL to skip most of the deterministic arithmetics. This can be useful to speed up the fuzzing of text-based file formats. @@ -377,22 +392,12 @@ checks or alter some of the more exotic semantics of the tool: Note that this setting inhibits some of the user-friendly diagnostics normally done when starting up the forkserver and causes a pretty significant performance drop. - - - Setting AFL_MAX_DET_EXTRAS changes the count of dictionary entries/extras - (default 200), after which the entries will be used probabilistically. - So, if the dict/extras file (`-x`) contains more tokens than this threshold, - not all of the tokens will be used in each fuzzing step, every time. - Instead, there is a chance that the entry will be skipped during fuzzing. - This makes sure that the fuzzer doesn't spend all its time only inserting - the extras, but will still do other mutations. However, it decreases the - likelihood for each token to be inserted, before the next queue entry is fuzzed. - Either way, all tokens will be used eventually, in a longer fuzzing campaign. - Outdated environment variables that are that not supported anymore: AFL_DEFER_FORKSRV AFL_PERSISTENT -## 4) Settings for afl-qemu-trace +## 5) Settings for afl-qemu-trace The QEMU wrapper used to instrument binary-only code supports several settings: @@ -446,7 +451,7 @@ The QEMU wrapper used to instrument binary-only code supports several settings: stack pointer in which QEMU can find the return address when `start addr` is hitted. -## 5) Settings for afl-cmin +## 6) Settings for afl-cmin The corpus minimization script offers very little customization: @@ -472,12 +477,12 @@ to match when minimizing crashes. This will make minimization less useful, but may prevent the tool from "jumping" from one crashing condition to another in very buggy software. You probably want to combine it with the -e flag. -## 7) Settings for afl-analyze +## 8) Settings for afl-analyze You can set AFL_ANALYZE_HEX to get file offsets printed as hexadecimal instead of decimal. -## 8) Settings for libdislocator +## 9) Settings for libdislocator The library honors these environmental variables: @@ -499,12 +504,12 @@ The library honors these environmental variables: - AFL_ALIGNED_ALLOC=1 will force the alignment of the allocation size to max_align_t to be compliant with the C standard. -## 9) Settings for libtokencap +## 10) Settings for libtokencap This library accepts AFL_TOKEN_FILE to indicate the location to which the discovered tokens should be written. -## 10) Third-party variables set by afl-fuzz & other tools +## 11) Third-party variables set by afl-fuzz & other tools Several variables are not directly interpreted by afl-fuzz, but are set to optimal values if not already present in the environment: diff --git a/docs/ideas.md b/docs/ideas.md index 65e2e8e6..a5d40963 100644 --- a/docs/ideas.md +++ b/docs/ideas.md @@ -3,49 +3,6 @@ In the following, we describe a variety of ideas that could be implemented for future AFL++ versions. -For GSOC2020 interested students please see -[https://github.com/AFLplusplus/AFLplusplus/issues/208](https://github.com/AFLplusplus/AFLplusplus/issues/208) - -## Flexible Grammar Mutator (currently in development) - -Currently, AFL++'s mutation does not have deeper knowledge about the fuzzed -binary, apart from feedback, even though the developer may have insights -about the target. - -A developer may choose to provide dictionaries and implement own mutations -in python or C, but an easy mutator that behaves according to a given grammar, -does not exist. - -State-of-the-art research on grammar fuzzing has some problems in their -implementations like code quality, scalability, or ease of use and other -common issues of the academic code. - -We aim to develop a pluggable grammar mutator for afl++ that combines -various results. - -Mentor: andreafioraldi - -## perf-fuzz Linux Kernel Module - -Expand on [snapshot LKM](https://github.com/AFLplusplus/AFL-Snapshot-LKM) -To make it thread safe, can snapshot several processes at once and increase -overall performance. - -Mentor: any - -## QEMU 5-based Instrumentation - -First tests to use QEMU 4 for binary-only AFL++ showed that caching behavior -changed, which vastly decreases fuzzing speeds. - -In this task test if QEMU 5 performs better and port the afl++ QEMU 3.1 -patches to QEMU 5. - -Understanding the current instrumentation and fixing the current caching -issues will be needed. - -Mentor: andreafioraldi - ## WASM Instrumentation Currently, AFL++ can be used for source code fuzzing and traditional binaries. @@ -66,20 +23,6 @@ Either improve a single mutator thorugh learning of many different bugs Mentor: domenukk -## Reengineer `afl-fuzz` as Thread Safe, Embeddable Library (currently in development) - -Right now, afl-fuzz is single threaded, cannot safely be embedded in tools, -and not multi-threaded. It makes use of a large number of globals, must always -be the parent process and exec child processes. -Instead, afl-fuzz could be refactored to contain no global state and globals. -This allows for different use cases that could be implemented during this -project. -Note that in the mean time a lot has happened here already, but e.g. making -it all work and implement multithreading in afl-fuzz ... there is still quite -some work to do. - -Mentor: hexcoder- or vanhauser-thc - ## Collision-free Binary-Only Maps AFL++ supports collison-free maps using an LTO (link-time-optimization) pass. diff --git a/docs/life_pro_tips.md b/docs/life_pro_tips.md index a5bd7286..0004c297 100644 --- a/docs/life_pro_tips.md +++ b/docs/life_pro_tips.md @@ -30,10 +30,10 @@ Check out the `fuzzer_stats` file in the AFL output dir or try `afl-whatsup`. It could be important - consult docs/status_screen.md right away! ## Know your target? Convert it to persistent mode for a huge performance gain! -Consult section #5 in llvm_mode/README.md for tips. +Consult section #5 in README.llvm.md for tips. ## Using clang? -Check out llvm_mode/ for a faster alternative to afl-gcc! +Check out instrumentation/ for a faster alternative to afl-gcc! ## Did you know that AFL can fuzz closed-source or cross-platform binaries? Check out qemu_mode/README.md and unicorn_mode/README.md for more. diff --git a/docs/perf_tips.md b/docs/perf_tips.md index 731dc238..fbcb4d8d 100644 --- a/docs/perf_tips.md +++ b/docs/perf_tips.md @@ -51,7 +51,7 @@ a file. ## 3. Use LLVM instrumentation When fuzzing slow targets, you can gain 20-100% performance improvement by -using the LLVM-based instrumentation mode described in [the llvm_mode README](../llvm_mode/README.md). +using the LLVM-based instrumentation mode described in [the instrumentation README](../instrumentation/README.llvm.md). Note that this mode requires the use of clang and will not work with GCC. The LLVM mode also offers a "persistent", in-process fuzzing mode that can @@ -62,12 +62,12 @@ modes require you to edit the source code of the fuzzed program, but the changes often amount to just strategically placing a single line or two. If there are important data comparisons performed (e.g. `strcmp(ptr, MAGIC_HDR)`) -then using laf-intel (see llvm_mode/README.laf-intel.md) will help `afl-fuzz` a lot +then using laf-intel (see instrumentation/README.laf-intel.md) will help `afl-fuzz` a lot to get to the important parts in the code. If you are only interested in specific parts of the code being fuzzed, you can instrument_files the files that are actually relevant. This improves the speed and -accuracy of afl. See llvm_mode/README.instrument_list.md +accuracy of afl. See instrumentation/README.instrument_list.md Also use the InsTrim mode on larger binaries, this improves performance and coverage a lot. @@ -110,7 +110,7 @@ e.g.: https://launchpad.net/libeatmydata In programs that are slow due to unavoidable initialization overhead, you may -want to try the LLVM deferred forkserver mode (see llvm_mode/README.md), +want to try the LLVM deferred forkserver mode (see README.llvm.md), which can give you speed gains up to 10x, as mentioned above. Last but not least, if you are using ASAN and the performance is unacceptable, diff --git a/docs/sister_projects.md b/docs/sister_projects.md index a501ecbd..640e59f7 100644 --- a/docs/sister_projects.md +++ b/docs/sister_projects.md @@ -52,7 +52,7 @@ options. Provides an evolutionary instrumentation-guided fuzzing harness that allows some programs to be fuzzed without the fork / execve overhead. (Similar functionality is now available as the "persistent" feature described in -[the llvm_mode readme](../llvm_mode/README.md)) +[the llvm_mode readme](../instrumentation/README.llvm.md)) http://llvm.org/docs/LibFuzzer.html @@ -245,7 +245,7 @@ https://code.google.com/p/address-sanitizer/wiki/AsanCoverage#Coverage_counters ### AFL JS (Han Choongwoo) One-off optimizations to speed up the fuzzing of JavaScriptCore (now likely -superseded by LLVM deferred forkserver init - see llvm_mode/README.md). +superseded by LLVM deferred forkserver init - see README.llvm.md). https://github.com/tunz/afl-fuzz-js diff --git a/docs/status_screen.md b/docs/status_screen.md index b89468ce..2eeb8f3f 100644 --- a/docs/status_screen.md +++ b/docs/status_screen.md @@ -324,7 +324,7 @@ there are several things to look at: - Multiple threads executing at once in semi-random order. This is harmless when the 'stability' metric stays over 90% or so, but can become an issue if not. Here's what to try: - * Use afl-clang-fast from [llvm_mode](../llvm_mode/) - it uses a thread-local tracking + * Use afl-clang-fast from [instrumentation](../instrumentation/) - it uses a thread-local tracking model that is less prone to concurrency issues, * See if the target can be compiled or run without threads. Common `./configure` options include `--without-threads`, `--disable-pthreads`, or |